# US 5,705,428 A · Method for preventing titanium lifting during and after metal etching > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,705,428 A - Document ID: US5705428A - Status: Granted - Kind: A - Application number: 08/511,063 - Filed: 1995-08-03 - Granted: 1998-01-06 - Earliest claimed: 1995-08-03 - Assignees: Chartered Semiconductor Manufacturing Pte Ltd. - Inventors: Lianjun Liu; Chiu-Kwan Man - Web page: https://patentgrep.com/patent/US5705428A ## CPC - H10P 50/287: {by chemical means} - H10P 50/266: {by vapour etching only} - H10P 50/267: {using plasmas} - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract A process for forming metal composites, using a titanium underlay as part of the composite, with reduced risk of titanium adhesion loss or lifting, has been developed. Several solutions, resulting in protective layers being formed on the exposed titanium sidewall, have been shown. One solution features the addition of nitrogen, as part of reactive ion etching chemistry, during the patterning of the underlying titanium layer. The resulting titanium nitride formation, on the exposed titanium sidewall, protects against subsequent processing steps that may degrade the adhesion of titanium to an underlying material. A second solution describes the formation of a titanium oxide film on the exposed titanium sidewall. This formation occurs during a photoresist plasma strip, using an oxygen-stream ambient. The titanium oxide film again results in protection of the titanium interface, during subsequent processing steps. ## Claims ### Claim 1 A method for forming metal patterns on a semiconductor substrate comprising the steps of: depositing a titanium layer on said semiconductor substrate; depositing a layer of titanium-tungsten on said titanium layer; depositing a layer of an aluminum based layer on said titanium-tungsten layer; forming a photoresist image on said aluminum based layer; anisotropically etching the exposed part of said aluminum based layer; anisotropically etching the exposed part of said titanium-tungsten layer; anisotropically etching the exposed part of said titanium layer using a reaction ambient, containing between about 5 to 80 sccm of N.sub.2, as one of the reactants, at a temperature between about 45.degree. to 70.degree. C. forming a titanium nitride film, between about 10 to 100 Angstroms in thickness, on the exposed sides of said titanium layer, during the anisotropic etching of said titanium layer; and removal of said photoresist image. ### Claim 2 (depends on 1) The method of claim 1, wherein said titanium layer is between about 200 to 2000 Angstroms. ### Claim 3 (depends on 1) The method of claim 1, wherein said titanium-tungsten layer is composed of between about 8 to 12% titanium, and between about 88 to 92% tungsten, deposited to a thickness between about 0 to 3000 Angstroms. ### Claim 4 (depends on 1) The method of claim 1, wherein said aluminum based layer is 100% aluminum, deposited to a thickness between about 4000 to 10000 Angstroms. ### Claim 5 (depends on 1) The method of claim 1, wherein said aluminum based layer contains between about 0 to 2% copper, by weight, and is deposited to a thickness between about 4000 to 10000 Angstroms. ### Claim 6 (depends on 1) The method of claim 1, wherein said anisotropic etching of the said aluminum based layer occurs in a mixture of between about 20 to 100 sccm of BCl.sub.3, and between about 20 to 80 sccm of Cl.sub.2. ### Claim 7 (depends on 1) The method of claim 1, wherein said anisotropic etching of said titanium-tungsten layer occurs in between about 10 to 80 sccm of SF.sub.6. ### Claim 8 (depends on 1) The method of claim 1, wherein said anisotropic etching of titanium layer occurs in an ambient comprised of between about 10 to 80 sccm of SF.sub.6, and between about 5 to 80 sccm of N.sub.2, at a temperature between about 45.degree. to 70.degree. C. ### Claim 9 (depends on 1) The method of claim 1, wherein said titanium nitride film, formed on the exposed sides of said titanium layer, is between about 10 to 100 Angstroms in thickness, formed during the etching of between about 200 to 2000 Angstroms of said titanium layer. ### Claim 10 (depends on 1) The method of claim 1, wherein said photoresist is removed via plasma ashing in 100% oxygen, at a temperature between about 100.degree. to 300.degree. C. ### Claim 11 A method for forming metal patterns on a semiconductor substrate, comprising the steps of: depositing a titanium layer on said semiconductor substrate; depositing a titanium-tungsten layer on said titanium layer; depositing an aluminum based layer on said titanium-tungsten layer; forming a photoresist shape on said aluminum based layer; anisotropically etching the exposed part of said aluminum based layer; anisotropically etching the exposed part of said titanium-tungsten layer; anisotropically etching the exposed part of said titanium layer; removal of said photoresist shape, in a plasma comprised of between about 500 to 4000 sccm of H.sub.2 O, and between about 20 to 100% O.sub.2 ; and formation of a titanium oxide film, between about 10 to 100 Angstroms in thickness, on the exposed sides of said titanium layer, formed during said photoresist shape removal process. ### Claim 12 (depends on 11) The method of claim 11, wherein said titanium layer is between about 200 to 2000 Angstroms. ### Claim 13 (depends on 11) The method of claim 11, wherein said titanium-tungsten layer is between about 0 to 3000 Angstroms. ### Claim 14 (depends on 11) The method of claim 11, wherein said aluminum based layer is 100% aluminum, and deposited to a thickness between about 4000 to 10000 Angstroms. ### Claim 15 (depends on 11) The method of claim 11, wherein said aluminum based layer contains between about 0 to 2% copper, by weight and is deposited to a thickness between about 4000 to 10000 Angstroms. ### Claim 16 (depends on 11) The method of claim 11, wherein said anisotropic etching of said aluminum based layer occurs in a mixture between about 20 to 100 sccm of BCl.sub.3, and between about 20 to 80 sccm of Cl.sub.2. ### Claim 17 (depends on 11) The method of claim 11, wherein said anisotropic etching of said titanium-tungsten layer occurs in between about 10 to 80 sccm of SF.sub.6. ### Claim 18 (depends on 11) The method of claim 11, wherein said anisotropic etching of said titanium layer occurs in between about 10 to 80 sccm of SF.sub.6. ### Claim 19 (depends on 11) The method of claim 11, wherein said photoresist is removed in a plasma, containing between about 500 to 4000 sccm of H.sub.2 O, and between about 20 to 100% of O.sub.2, at a temperature between about 100.degree. to 300.degree. C. ### Claim 20 (depends on 11) The method of claim 11, wherein said titanium oxide film, is formed to a thickness between about 10 to 100 Angstroms, on the exposed sides of said titanium layer, during the removal of said photoresist shape. ### Claim 21 A method for forming metal patterns on a semiconductor substrate, comprising the steps of: depositing a titanium layer on said semiconductor substrate; depositing a titanium-tungsten layer on said titanium layer; depositing an aluminum based layer on said titanium-tungsten layer; forming a photoresist shape on said aluminum based layer; anisotropically etching exposed part of said aluminum based layer; anisotropically etching exposed part of said titanium-tungsten layer; anisotropically etching exposed part of said titanium layer, in an ambient containing between about 5 to 80 sccm of N.sub.2 as one of the reactants, using N2 as one of the reactants; forming a titanium nitride layer, between about 10 to 100 Angstroms in thickness, on the exposed sides of said titanium layer, during the anisotropic etching of said titanium layer; and removal of said photoresist shape in an oxygen-steam plasma, forming an aluminum oxide film, on the exposed sides of said aluminum based layer. ### Claim 22 (depends on 21) The method of claim 21, wherein said anisotropic etching of said titanium layer occurs in between about 10 to 80 sccm of SF.sub.6, and between about 5 to 80 sccm of N.sub.2. ### Claim 23 (depends on 21) The method of claim 21, wherein said titanium nitride film, formed on exposed sides of said titanium layer to a thickness between about 10 to 100 Angstroms, and formed during the anisotropic etching of between about 200 to 2000 Angstroms of said titanium layer. ### Claim 24 (depends on 21) The method of claim 21, wherein said photoresist is removed in a plasma containing between about 500 to 4000 sccm of H.sub.2 O, and between about 20 to 100% oxygen.